(a) Field of the Invention
The present invention relates to a novel structure of a touch panel, in particular to a touch panel structure having the advantages of a relatively low material cost, a light weight, an easy manufacturing and molding process, a better lamination yield and a flexible and break-free feature.
(b) Description of the Related Art
Touch panel is mainly divided into resistive, capacitive, surface acoustic wave, or optical IR touch panel according to its different sense method. Among them, resistive and capacitive touch panels are used widely, wherein the structure of the resistive touch panel seems a sandwich, the top layer is an transparent conductive plastic film and the down layer is a conductive carrier, dot spacers are filled with between them and a voltage of 5V is introduced. The top layer will touch the down layer when it is touched (or knock little) by a finger or a pen, and a delta voltage (ΔV) will be produced An A/D controller will converts the delta voltage into a digital signal provided for a computer to compute (X,Y)-axes positions to achieve a excellent position accuracy.
Basically, the capacitive touch panel improves the scratch resistance of the resistive touch panel and solves the circuit break issue that will cause a failure of the touch panel if the top layer (the transparent conductive film) is scratched seriously. With reference to FIG. 1 for a basic structure of a conventional capacitive touch panel, the outermost layer is an anti-scratch layer 11 made of glass, and the second layer is a capacitive sensor structure 12 covered by the anti-scratch layer 11, and the capacitive sensor structure 12 adopts both sides of a single sheet glass 121 to form an X-axis-wise capacitive sensor layer 122 and a Y-axis-wise capacitive sensor layer 123 (or adopts two glass pieces to form the X-axis-wise and Y-axis-wise capacitive sensor layers on a single side of each glass piece, such that a uniform electric field is produced between the X-axis-wise capacitive sensor layer 122 and the Y-axis-wise capacitive sensor layer 123 as shown in FIG. 2 and provided for sensing a weak current of a human body to achieve a touch control effect.
In the conventional touch panel as shown in FIG. 1, the anti-scratch layer 11 and capacitive sensor structure 12 are glass substrates. Although the capacitive sensor structure 12 can be manufactured by etching (a photolithography process included in color filtered) and the pattern by this way is not visible, the cost of the required equipments and manufacturing processes are too high and not cost-effective. Furthermore, a transparent lamination layer 13 is used as a linking bridge or is pasted to a surface of an LCD panel 16. The glass-to-glass lamination method, which the both layer are so hard, not only results in a poor lamination yield, but also has difficulties to get a good accuracy and arises into a risk of breaking the panel easily.
There is another type of touch panel structures as shown in FIG. 3 available in the market, and a capacitive sensor structure 14 of this conventional touch panel includes two transparent conductive plastic films 141, 142 formed on an X-axis-wise capacitive sensor layer and a Y-axis-wise capacitive sensor layer respectively, and a transparent lamination layer 13 is used to paste the two transparent conductive plastic films 141, 142. Similarly, an anti-scratch layer 11 made of glass is pasted to the top of the capacitive sensor structure 14 by the transparent lamination layer 13, and another transparent conductive plastic film 15 as an EMI shielding function is pasted to the bottom of the capacitive sensor structure 14.
However, the conventional touch panel as shown in FIG. 3 has a relatively complicated structure and high material and manufacturing costs, and the capacitive sensor layers of the transparent conductive plastic films 141, 142 are produced by a traditional screen printing etching method, and whose capacitive sensor pattern has a relatively low precision. In addition, the anti-scratch layer 11 is also made of glass, and has the same issues of a low lamination yield r, a high cost and a risk of breaking the panel easily. The touch panel is formed by stacking and combining a plurality of sensor layers and insulat layers, not only resulting in a thicker panel, but also decreasing the light transmission of the touch panel substantially.